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Info from the old A:M FAQ?

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Would folks be interested in information from the old 'killernuts' A:M FAQ?

A lot of it is outdated but there are some real gems in there.


Here's a random sampling:


When discussing lighting, I have seen people say things like "I used a basic three light setup...". I have no idea what this means. I'm assuming that there is some understanding of common lighting techniques, possibly from photography or film, that I don't share.


OK, a somewhat simplistic roundup:


In general, all the aspects of the CG world that mimic real-world cinematography, eg camera and actor blocking/positioning, lighting , lens choice, composition within the frame, repay study of the real world equivalents (and of books written about them!) Lighting in cinematography and CG is a huge subject!


The "three light setup" is a basic of portrait photography - the idea is to try to accentuate the 3D structure of the subject, by avoiding them looking flat (which is why those photo-booth pics always look so terrible) - essentially you have:


one bright light (Key-light), a bit above, in front and to one side - this provides the main lighting on the character, but tends to leave large very dark shadows across one side of the face, so you use....


a dimmer light (Fill-light) a bit above, in front and to the opposite side - this avoids having pitch black shadows from the key-light


a third light (Back-light) usually positioned below and behind the subject, pointing up and forward - the purpose of this is to produce a lit edge to the subject, separating them from the background


number - more lights = longer renders, but more control over the appearance of the scene - depends what you are trying to do - most movies use complicated lighting setups to draw attention to exactly the required elements within the scene - individual subjects/objects in the scene may even have their own 3-light setups


types - most of the indoor setups mimicking studio scenes would be using Kliegs (= spotlights). Outdoor scenes may use a Sun - which produces parallel light rays. The Bulb is like a naked lightbulb, producing light in all directions equally


colours - outdoor daytime is bluish light ( and by cinematic convention outdoor night-time lighting tends to be bluish too!) Indoor artificial light tends to be more yellow. Fluorescent can have a slightly greenish tinge. Traditional cinematic and theatrical lighting will often use different colours for the components of a three light setup, such as a bluish Key, and more yellow fill and backlights.


positioning - classic 3-light already discussed - some lights may be in-shot, most will not. (Think of the way in which in old movies, a spotlight was used to fake the illumination provided by a candle carried by a character) Gothic - key below, in front, pointed up. Comedy - bright even lighting. Drama - more emphasised keylight. Filmnoir - just Keylight.


Spotlights were often used to pick out a characters eyes in classic movies, but now less often ( for a recent example, see Anjelica Huston as Morticia in either of the "Addams Family" movies)


Ambience and Radiosity - in the real world, light bounces around from object to object, and may pick up some colouration from objects as it does so. In the computer, we can mimic this to some extent, in several ways. We can use a non-zero ambience (default is 20% in AM, which for many purposes is probably too high, and makes things look a bit flat). We can do a radiosity precalulation - which takes ages, and has a subtle effect similar to setting the ambience a bit higher :-) as far as I can see. Or we can use more fill-lights, which probably gives us most control. Outdoor daytime scenes tend to have higher ambience and look flatter, whereas indoor night-time scenes may have more obviously directional lighting ( and even more so for space scenes).


There's no substitute for reading some books on cinema lighting, and for experimenting with lighting in a simple scene in AM.


Also read the AM99 v7.1 manual (if you haven't already done so, download it!) which discusses the different light types, and issues about radiosity, specularity, heirarchical lights, and light lists ( which allow you to only illuminate specific objects) Also have a look at the documentation on different types of shadow production, and the control over this that AM gives you.


Dave Corcoran

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Here's one on lipsync:


Any tips on animating mouth shapes for lip-syncing?


For Bs and Ps at least, the mouth is closed far in advance of the sound. Prior to the sound, the mouth is closed to form a seal that allows the air pressure to build up inside the mouth, and the B or P sound is the percussive sound made when that air pressure is released suddenly. The primary difference between the two is that a B sound is made in while the vocal chords are already producing sound, and with the P sound the vocal chords are actuated slight after the percussive sound caused by the sudden release of air.


An M sound doesn't involve the buildup of air in the mouth, but rather the vocal chords are producing sound while the mouth is closed, and the air is being released through the nose.


The upshot of this is that the mouth should close at least a couple of frames before you hear the B, P or M sounds. An M sound actually precedes the vowel that follows it, but for practical purposes the lips close prior to what we count as hearing the M sound the same as B or P.


This is also true of V and F sounds, the V more or less being an F with the vocal chords making sound. Consonants like G, J, or K sounds are less critical because they occur inside the mouth and can't be seen clearly most of the time.


Vowels generally seem to work best when they're timed as you read them, that is they neither lead nor trail the sounds as you read them off the track.


Steph Greenberg

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And one on everyone's favorite animate button:


This is such a stupid question I don't even want to ask it, but how in the world do you position an object in the choreography on a frame other than 0 so that it does not set keyframes for moving or rotating it to get to that position.


I am sure AM can do this I just don't know how.


In the properties dialog of the choreography instance of the object you want to manipulate, go to the first tab and there will be a variety of check boxes one of which is labelled "animate", just uncheck it, then remember to recheck it if you want to add more keyframes later.


Matt Andersen



Another factoid: All of these Questions were asked and answered via email (courtesy of Hash Inc's animaster listserver).

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Curving water anyone?


How can I animate water curving around a bend?


This tip is just so you can get the water to curve. If you created your water object, then in action straighten the water out so it doesn't curve applly your straight animated water texture. Now thanks to the wonders of HASH UV mapping the water will curve around the bend!



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A few words about Quaternion interpolation:


Under the Action panel in the Options windows, Interpolation now offers Vecter Eular and Quat.


What's Quat? v6 only offered Vector and Eular.




Quaternion interpolation achieves the smoothest possible interpolation between any possible keyframes, and suffers no side effects such as a sweet spot or preferred roll region. However, a human does not easily decipher the values stored in the channels. The channels can however be used to adjust the magnitude, timing, softness and ease of the rotational transitions. Understanding the values in the channels should not be necessary to make those adjustments. For those of you that just must know, the four values in the channels consist of x-quat, y-quat, and z-quat, which hold a vector that represents the axis of rotation.


So (80,0,0) would indicate that the bone is being rotated around the x-axis. The w-quat value holds a number that represents how much it was rotated. However this number is not in degrees, rather it is the cosine of half of the angle, scaled up by 100 for easier viewing in the channels. These numbers range from -100 to 100, 100 means no rotation, and -100 which represents 360 degrees. A w-quat value of 0 represents a 180 degree rotation about the axis specified in x-quat, y-quat, and z-quat.


Jeff C


I believe Jeff is just quoting from the technical reference here.

He was often good for reminding folks to RTFM. ;)

He was however probably the first person in the A:M Comunity to reach out and contact me privately via email to answer a question and help to resolve a difficulty I was having.

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Mouse motion capture anyone?


Anybody found how to use mouse mocap? It's mentioned in the AM99 features.doc.


While the play button is down move bones or muscle points around and they will be recorded. You can see it on the next loop if you have the repeat button down


Will P., Hash Inc.

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(complex) Action Objects?


I just took a look at Mike Caputo's very interesting article in 3d Artist about action objects. I hadn't realized that they could be used for so much --but I was wondering about their limitations, too. Mike has a character lift an action object. (a barbell) I was just wondering if you could bring in 2 say fully constrained characters (maybe both are wrestlers, say) -- into action together--one being your model, and another character being an action object. Can you bring in a full set into action as action objects?


Absolutely. I kept the example simple, but there's no limit to the feature.


It's really designed to allow you to animate two characters together.



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